Incomplete Punctal Canalization

Abstract

Incomplete punctal canalization is a term that refers to a form of punctal dysgenesis with membranes [1–5]. The term was first described by Ali et al. [1], who studied 55 such dysgenetic puncta. The pathogenesis of punctal membranes is unknown but is believed to either represent failed dehiscence of epithelium overlying the normally formed canaliculi or failure of canalization of the most proximal part of lacrimal apparatus. Patients typically present in the first decade with symptoms of epiphora since birth or infancy. Clinical examination reveals punctal membranes which could be external or internal. The external membrane (EM) variety, which is also called IPC-EM, typically covers the external surface of the puncta and hides it beneath, giving a false impression of punctal agenesis (Fig. 22.8). The internal membrane (IM) variety, which is also called IPC-IM, typically demonstrates blurred punctal margins but, just at the entry into the puncta, covers it entirely with a membrane. The membranes usually appear translucent (Fig. 22.9). Clinical diagnosis is based on high degree of suspicion and slight avascular dimple at the site of puncta, and the membrane tends to stand out as a translucent structure from the surroundings if indirect illumination is used with the help of slit lamp and a thin slit beam is placed perpendicular and adjacent to the punctum. The punctal membranes on histopathological examination uniformly are fibrovascular membranes without any signs of inflammation.